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Marijuana Use Linked to Increased Car Crashes

Although the workplace impact of marijuana in states where it’s been legalized has mainly been a workers compensation concern, a recent study now links marijuana use to increased auto crash claims.

In four states where marijuana is now legal — Colorado, Nevada, Oregon and Washington — the frequency of collision claims filed with insurers were higher in recent years, according to new research by the Insurance Institute for Highway Safety (IIHS) and Highway Loss Data Institute (HLDI).

In the IIHS study, researchers compared the change in crash rates in Colorado, Oregon and Washington with the change in crash rates in the neighboring states that didn’t enact recreational marijuana laws. Colorado was compared with Nebraska, Wyoming and Utah, and Oregon and Washington with Idaho and Montana. The study controlled for differences in demographics, unemployment and weather in each state.

The problem — and what these studies address — is that the role marijuana plays in crashes isn’t as clear as the link between alcohol and crashes. Many states don’t include consistent information on driver drug use in crash reports, and policies and procedures for drug testing are inconsistent. More drivers in crashes are tested for alcohol than for drugs. When drivers are tested, other drugs are often found in combination with alcohol, which makes it difficult to isolate their separate effects.

“The new IIHS-HLDI research on marijuana and crashes indicates that legalizing marijuana for all uses is having a negative impact on the safety of our roads,” says IIHS-HLDI President David Harkey. “States exploring legalizing marijuana should consider this effect on highway safety.”

In addition to the states studied, Alaska, California, Maine, Massachusetts, Vermont and the District of Columbia also allow recreational use of marijuana for adults 21 and older and medical use of marijuana. Twenty-two other states allow medical marijuana, and 15 more states permit its use for designated medical conditions.

Plus, legalization for recreational use is pending in New Hampshire, New Jersey, New York and Pennsylvania. In November, Michigan and North Dakota will hold referendums on marijuana, and Missouri and Utah voters will decide whether to expand medical marijuana laws in their states.

Still Illegal under Federal Law

Marijuana may be raising safety concerns, but it’s unlikely that this will have any impact on its growth in popularity. Still, under federal law, Marijuana remains an illegal controlled substance.

For the most part, however, the federal government has taken a hands-off approach to state legalization. So as a practical matter, in those states where it’s legal or becoming legal, there is no impediment to its use.

Practical Limitations on Testing for Marijuana Use

Even if there may be increased concerns about safety issues related to marijuana use, there are practical and legal limitations for employers who adopt a no drug tolerance policy. While someone may test positive while on the job, that result may simply be evidence that the employee used marijuana several weeks ago and has not in any way been impaired while at work.

The problem is it’s difficult to determine if someone is under the influence of marijuana. Unlike alcohol, the amount present in a person’s body doesn’t consistently relate to impairment. The primary psychoactive component of cannabis is THC, or Tetrahydrocannabinol. However, even if a driver tests positive for THC it doesn’t mean the driver was impaired at the time of the crash. Habitual users of marijuana may have positive blood tests for THC days or weeks after using the drug.

Nevertheless, according to Harkey, “Despite the difficulty of isolating the specific effects of marijuana impairment on crash risk, the evidence is growing that legalizing its use increases crashes.”